<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let num = +prompt('请您输入值')
        switch(num) {
            case 1:
                document.write('原来你是1啊')
                break;
            case 2:
                document.write('你你你')
                break;
            case 3:
                document.write('哈哈哈')  
                break;
            default:
                document.write('都不对')
                break;
        }
    </script>
</body>
</html>